In a 401k? Yes. But if you read the article:

Today, wealthy taxpayers can protect up to $452,500 per year in tax-advantaged accounts in a single year, saving up to $203,600 on their taxes. And they can keep their money in tax-advantaged accounts far longer.

There are many types of tax-advantaged accounts.

https://www.investopedia.com/terms/t/tax-advantaged.asp

23k is the max annual contribution

If you’re over 50, you can put $30,500 in your 401k, the extra $7500 per year is called a ‘catch-up contribution’